Issue 21, 1996

Synthesis, molecular structure and palladium(II) and platinum(II) complex chemistry of 3-(ferrocen-1-yl)-1-(pyridin-2-yl)pyrazole

Abstract

Treatment of the potassium salt of 3(5)-(ferrocen-1-yl)pyrazole L1 with 2-bromopyridine in diglyme (2,5,8-trioxononane) at 130 °C for 3 d, followed by an aqueous quench, yielded the compound 3-(ferrocen-1-yl)-1-(pyridin-2-yl)pyrazole L2 in 37% recrystallised yield. A single-crystal structure determination of L2 confirmed the proposed 1,3-disubstitution pattern at the pyrazole ring, the substituted cyclopentadienyl and two heterocyclic rings being approximately coplanar. Treatment of L2 with a stoichiometric amount of [{MCl(C3H5)}x](M = Pd, x= 2; M = Pt, x= 4) and NH4PF6 gave [M(η3-C3H5)(L2)]PF6(M = Pd 1 or Pt 2) while a similar reaction with [PdCl2(NCPh)2] afforded [PdCl2(L2)]3. Treatment of 3 with 1 molar equivalent of K2C2O4, Na2(cat) or Na(acac)–NH4PF6 yielded [Pd(L)L2][L = C2O42–4 or catecholate (cat)5] and [Pd(acac)(L2)]PF66(acac = acetylacetonate) as analytically pure solids. The 1H NMR behaviour of 46 is complex and suggestive of extensive ligand dissociation in solution; molecular models imply that this may reflect steric interactions between the pendant ferrocenyl moiety and metal-bound anionic chelate O-donors. The UV/VIS and electrochemical data show that the ferrocenyl group becomes significantly electron-poorer upon co-ordination of L2, reflecting an inductive interaction with the co-ordinated M2+(M = Pd or Pt) electrophiles.

Article information

Article type
Paper

J. Chem. Soc., Dalton Trans., 1996, 4055-4061

Synthesis, molecular structure and palladium(II) and platinum(II) complex chemistry of 3-(ferrocen-1-yl)-1-(pyridin-2-yl)pyrazole

R. J. Less, J. L. M. Wicks, N. P. Chatterton, M. J. Dewey, N. L. Cromhout, M. A. Halcrow and J. E. Davies, J. Chem. Soc., Dalton Trans., 1996, 4055 DOI: 10.1039/DT9960004055

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